1. Field of the Invention
The present invention relates to gel preparations for external application containing diclofenac sodium as active ingredient and having good stability and nice feeling on use.
2. Description of the Prior Art
Diclofenac sodium is a derivative of phenylacetic acid represented by the formula: ##STR1## which is a non-steroid drug soluble in water and alcohols having excellent antiinflammatory and analgetic effects. For the present, it is used only in the form of oral preparations or suppositories and shows excellent antiinflammatory and analgetic effects. However, side effects such as stomach and intestines trouble, liver trouble and kidney trouble, are at issue, especially in the case of the oral administration. Therefore, antiinflammatory and analgetic preparations which are absorbed cutaneously without showing such side effects are desired.
In this regard, a gel preparation for external application containing indomethacin, a non-steroid drug, is known (Japanese Patent Laid-open No. Sho 53(1978)-81616). In this preparation, however, there is a question of stability and there is a defect that its yellow color due to the color of indomethacin itself soils clothes as it is applied on the skin. Thus, the inventor of the present invention has found preparations for external application which consist of a solution comprising another non-steroid compound having antiinflammatory and analgetic effects, at least one of peppermint oil and salicylic acid ester in an amount sufficient to dissolve the non-steroid compound and a base for external application (Japanese Patent Application No. Sho 56(1981)-128032). However, only water-insoluble compounds having antiinflammatory and analgetic effects may be used in such preparations.